The present invention is directed toward the inspection of eccentric bushings and, more particularly, toward inspection devices and methods for checking an eccentric bushing to determine the amount and direction of the offset of the eccentric bushing.
As is well known, an eccentric bushing is a bushing having a cylindrical exterior surface and a cylindrical interior bore, wherein the axis of the interior bore is not coaxial with the axis of the cylinder defined by the exterior surface, i.e., the axis of the interior bore is offset from the axis of the exterior surface. Eccentric bushings are used in various applications, including automotive applications. In some of these applications, it is necessary to determine the amount and/or direction of the offset of the axis of the interior bore from the axis of the exterior surface. One method that has been used to make this determination utilizes a cylindrical mount and a dial test indicator, wherein the mount is held by a metal holding device, such as a vice, and the dial test indicator is mounted to the holding device using a magnetic base. The eccentric bushing is disposed over the mount and a pivotable actuator rod of the dial test indicator is disposed against an exterior surface of the bushing. The eccentric bushing is then rotated around the mount, i.e., around the axis of the interior bore. Since the axis of the exterior surface is not coaxial with the axis of the interior bore, the exterior surface will pivot the actuator rod as the eccentric bushing is rotated. This pivotal movement of the actuator rod is amplified and displayed by a gauge of the dial test indicator. Using readings from the gauge, the amount and/or direction of the offset of the axis of the interior bore can be determined.
The foregoing prior art apparatus and method for inspecting eccentric bushings has several disadvantages. If the exterior surface is not perfectly cylindrical, inaccuracies are introduced into the readings. In addition, in order to permit the eccentric bushing to be rotated, there must sufficient clearance between the eccentric bushing and the mount. This clearance, however, permits the axis of the interior bore to shift, which also introduces inaccuracies into the readings. Accordingly, it is desirable to minimize the clearance between the eccentric bushing and the mount, which requires the mount to have a diameter specifically tailored for the interior bore of the eccentric bushing. Thus, multiple mounts must be provided in order to inspect eccentric bushings having interior bores with different dimensions, and even with these multiple mounts, the clearances (and, thus, the inaccuracies) cannot be totally eliminated.
Therefore, there exists a need in the art for an improved inspection device and method for checking an eccentric bushing, wherein the inspection device and the method can be used with eccentric bushings having interior bores with different diameters and exterior surfaces that are not perfectly cylindrical. The present invention is directed to such an inspection device and method.